I want my 100MB switch out for a 1GB in my OEL5 linux server, there is a way to configure in the NIC (Network Interface card) supports to 1Gb speed manually.
The speed of a port can be set to 10MB, 100MB, or 1000MB (1GB), if your network is supported up to 1000MB (1GB), it's best to hard set them to 1000MB (1GB).


[root@hostname ~]# ethtool eth0

Settings for eth0:

        Supported ports: [ TP ]

        Supported link modes:   10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

                                1000baseT/Full

        Supports auto-negotiation: Yes

        Advertised link modes:  Not reported

        Advertised auto-negotiation: No

        Speed: 100Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 1

        Transceiver: internal

        Auto-negotiation: off

        Supports Wake-on: g

        Wake-on: d

        Link detected: yes

 

[root@hostname ~]# cd /etc/sysconfig/network-scripts/

[root@hostname network-scripts]# ls

ifcfg-eth0      ifdown-eth     ifup          ifup-post

ifcfg-eth0.old  ifdown-ippp    ifup-aliases  ifup-ppp

ifcfg-eth1      ifdown-ipsec   ifup-bnep     ifup-routes

ifcfg-eth2      ifdown-ipv6    ifup-eth      ifup-sit

ifcfg-eth3      ifdown-isdn    ifup-ippp     ifup-sl

ifcfg-eth5      ifdown-post    ifup-ipsec    ifup-tunnel

ifcfg-eth6      ifdown-ppp     ifup-ipv6     ifup-wireless

ifcfg-eth7      ifdown-routes  ifup-ipx      init.ipv6-global

ifcfg-lo        ifdown-sit     ifup-isdn     net.hotplug

ifdown          ifdown-sl      ifup-plip     network-functions

ifdown-bnep     ifdown-tunnel  ifup-plusb    network-functions-ipv6

 

[root@hostname network-scripts]# more ifcfg-eth0

# Broadcom Corporation NetXtreme II BCM5708 Gigabit Ethernet

DEVICE=eth0

BOOTPROTO=static

DHCPCLASS=

ETHTOOL_OPTS="speed 100 duplex full autoneg off"

HWADDR=00:11:10:89:99:FC

IPADDR=10.100.100.101

NETMASK=255.255.255.0

ONBOOT=yes

 

[root@hostname network-scripts]# vi ifcfg-eth0

# Broadcom Corporation NetXtreme II BCM5708 Gigabit Ethernet

DEVICE=eth0

BOOTPROTO=static

DHCPCLASS=

ETHTOOL_OPTS="autoneg on"

HWADDR=00:11:10:89:99:FC

IPADDR=10.100.100.101

NETMASK=255.255.255.0

ONBOOT=yes

 

Restart the Network service after completed the configuration

[root@hostname network-scripts]# service network restart

Shutting down interface eth0:                              [  OK  ]

Shutting down loopback interface:                          [  OK  ]

Bringing up loopback interface:                            [  OK  ]

Bringing up interface eth0:                                [  OK  ]

[root@hostname network-scripts]# ethtool eth0

Settings for eth0:

        Supported ports: [ TP ]

        Supported link modes:   10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

                                1000baseT/Full

        Supports auto-negotiation: Yes

        Advertised link modes:  10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

                                1000baseT/Full

        Advertised auto-negotiation: Yes

        Speed: 1000Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 1

        Transceiver: internal

        Auto-negotiation: on

        Supports Wake-on: g

        Wake-on: d

        Link detected: yes

[root@hostname network-scripts]#